Thermal Modalities Flashcards
Conduction
the gain or loss of heat resulting from direct contact between two materials at different temps
Examples: hot/cold pack, paraffin
Convection
the gain or loss of heat resulting from air or water moving in a constant motion across the body
Examples: fluidotherapy, hot/cold whirlpool
Radiation
direct transfer of heat from a radiation energy source of higher temperature to one of cooler temp
Examples: infrared (IR) lamp, ultraviolet (UV) light, laser
Evaporation
transfer of heat that occurs as liquid absorbs energy and changes form into vapor
Examples: sweat, vapocoolant spray
Conversion
heating that occurs when non-thermal energy (i.e., mechanical, electrical) is absorbed into tissue and transformed into heat
Examples: ultrasound (US), diathermy
Physiological Effects
Cellular/metabolic
- Increased metabolic rate
Vascular
- Increased capillary permeability
- Increased blood flow velocity (vasodilation)
Neuromuscular
- Decreased pain
- Decreased muscle spasm
- Decreased tone
- Increased nerve conduction
Connective tissue
- Increased collagen extensibility
- Increased muscle elasticity
Vascular Effects (Vasodilation)
Axon Reflex: peripheral nerve stimulated, sending antidromic response to stimulate target organs
Release of chemical mediators: Increased capillary hydrostatic pressure and permeability. Promotes fluid filtration from vascular -> extravascular space
Local spinal cord reflexes: Decrease in sympathetic activity. Decrease in smooth muscle activity of blood vessels
CT Viscoelastisity
Heat and stretching = plastic deformation
Efficacy depends on: Temperature elevation (site, time, amount), Stretch (duration, amount, velocity)
Decreased joint stiffness
Increased muscle flexibility
Permanent elongation of CT
Constant load of enough magnitude to overcome tissue elasticity
Rapid stretch followed by a period of holding in that position
Constant rate of stretching using a slow, steady stretch
Low load long duration (LLLD)
Less tissue damage
Greater increases in joint ROM
Temperature Variables for Physiological Change
Therapeutic range: between 40°C and 45°C (104°F and 113°F)
Rate at which energy is being added to the tissue
Volume of tissue exposed
Composition of the absorbing tissue
Capacity of the tissue to dissipate heat (largely a factor of blood supply)
Heating Modality Parameters
Superficial heating modalities: tissues to depths of 0.5–2.0 cm
Deep thermotherapy: tissue depths of 3–5 cm
Maximum temperature within 6–8 minutes of exposure
Treatment time usually is 15–30 minutes, allows for maximum tolerable increases in tissue temp, blood flow
Longer duration for deeper tissue
After peak temperature is reached, there is a plateau or slight decrease in temp
After thermal modality is removed, tissue temp will decrease to non- therapeutic range in 5 minutes.
Indications
Decrease pain
Increase connective tissue extensibility
Reduce joint stiffness
Decrease muscle spasm
Increase ROM
Facilitate tissue healing by increasing blood flow
Heat Preperation
Explain treatment and expected sensations
Inspect skin and check sensation prior to treatment
Make sure patient can alert you if necessary
Dry and inspect skin at conclusion of treatment
Hot Packs
Moist (70–75°C/158–167°F)
Hydrocollator water temperature between 165–170°F
6–8 layers of toweling will be needed to prevent burns
Commercial hot-pack covers: four layers of toweling Treatment time: 15–20 minutes
Electric/microwavable heating pads
Long duration, lower-level heat
Good for home use pain reduction
Air-activated heat wraps
Can be work up to 8–10 hours at a time
Heat up to 40°C
Can be worn during ADLs, sleep, work
Paraffin Wax
Usually molten between 45–54ºC (118–130ºF)
Low specific heat
Low thermal conductivity
Oils in wax moisturize skin
Techniques: Dip and wrap, Dip and immerse, Pain application
Uses: Painful joints (arthritis), ; RA**
